The invention relates to centrifugal separators, e.g., self-cleaning centrifugal separators having an axially displaceable piston or sliding valve which, upon the release of the control fluid from the closing chamber by means of an actuable release valve, is shifted to its open position under the pressure of the drum contents, thus uncovering an annular gap for the ejection of the solids. Such a drum is disclosed, for example, in German Pat. No. 2,041,371, and U.S. Pat. No. 3,754,701.
In drums of this kind a discharge or release passage leads from the radially outermost portion of the closing chamber to a release valve which, according to the position of the release valve body, connects this discharge passage to a passage leading out of the drum or separates it therefrom. Since experience shows that two or more valves cannot be operated synchronously, in general, only one release valve is provided.
After the emptying of the closing chamber has been initiated, it may happen that the slide valve will be tilted in its movement into the open position, which can be attributed only to the fact that the force acting on the sliding valve is not relieved uniformly over the entire circumference owing to the one-sided release of the closing fluid, i.e., that the free fluid level in the closing chamber will not retain its concentric shape. Upon the abrupt release of the discharge passage, which has a relatively large cross section, a flow gradient and hence a pressure gradient will develop from the point diametrically opposite the release passage to the release passage, so that the sliding valve is acted upon more strongly from the closing chamber in the area remote from the release valve than in the area adjacent the release valve, and consequently assumes a tilted position.